Diffraction-based light beam scanner

Abstract

System and method utilizing a reconfigurable in real-time phase-modulating diffractive device (in a specific case—a 2D array of micro-mirror elements) in conjunction with another diffractive element (active or passive) to spatially steer a beam of polychromatic light such that light reaches the identified target without being substantially angularly dispersed.

The invention claimed is: 
     
       1. A method for relaying a light beam through an optical system, the method comprising:
 impinging a first polychromatic light beam having a first degree of divergence and a first wavelength spectrum onto a first diffractive element to produce a second polychromatic light beam having a second degree of divergence and a second wavelength spectrum, the second degree of divergence being different from the first degree of divergence, the first and second wavelength spectra being substantially equal; and 
 causing said second polychromatic light beam to interact with a second diffractive element to form a third polychromatic light beam having a third wavelength spectrum and a third degree of divergence, the second and third wavelength spectra being substantially equal, the first and third degrees of divergence in space being substantially equal. 
 
     
     
       2. The method according to  claim 1 , wherein the impinging includes
 receiving a substantially collimated first polychromatic light beam at the first diffractive element, and 
 forming, from the substantially collimated first polychromatic light beam, the second polychromatic light beam that is spatially diverging. 
 
     
     
       3. The method according to  claim 1 , wherein said interacting includes producing the third polychromatic light beam that is substantially collimated. 
     
     
       4. The method according to  claim 1 , further comprising changing an operational characteristic of the second diffractive element to spatially steer the third polychromatic light beam. 
     
     
       5. The method according to  claim 4 , wherein the changing includes changing the operational characteristic of the second diffractive element to spatially steer the third polychromatic light beam while keeping said third polychromatic light beam substantially collimated, the third polychromatic light beam containing light at multiple wavelengths. 
     
     
       6. The method according to  claim 1 , further comprising causing a change in an angular direction of propagation of the third polychromatic beam, while keeping the third polychromatic beam substantially collimated, by spatially chirping a period of a diffraction grating formed at the second diffractive element. 
     
     
       7. The method according to  claim 6 , wherein said causing includes causing the third polychromatic beam change its angular direction of propagation in a spatially-discreet fashion. 
     
     
       8. The method according to  claim 1 , wherein the causing to interact includes
 while spatially steering said first polychromatic light beam, forming said third polychromatic light beam that is directed along an axis that is transverse to an output surface of the second diffractive element regardless of an angle of incidence of the first polychromatic light beam onto the first diffractive element. 
 
     
     
       9. The method according to  claim 1 , wherein the causing said second polychromatic light beam to interact with the second diffractive element includes
 while spatially steering said first polychromatic light beam, forming said third polychromatic light beam that is directed along an axis that is substantially perpendicular to an output surface of the second diffractive element regardless of an angle of incidence of the first polychromatic light beam onto the first diffractive element. 
 
     
     
       10. The method according to  claim 1 , wherein any of said first and second diffractive elements includes a two-dimensional (2D) array of micro-reflectors, wherein an operation of each of said micro-reflectors is defined by discrete spatial orientations of such micro-reflector. 
     
     
       11. The method according to  claim 10 , comprising impinging light onto at least one of the first and second diffractive elements while activating the 2D array of micro-reflectors that form a surface of said at least one of the first and second diffractive elements, to define a chirped diffraction grating at said at least one of the first and second diffractive elements. 
     
     
       12. The method according to  claim 1 , wherein one of said first and second diffractive elements is configured as a chirped diffraction grating. 
     
     
       13. The method according to  claim 1 , wherein said relaying includes relaying light through a monostatically-configured system.